Accelerated pubertal onset in short children with delayed bone age.

OBJECTIVES Constitutional delay of growth (CDG) is usually associated with a delay in pubertal onset (CDGP) and a catch-up growth after puberty. Some individuals, however, have earlier-than-expected pubertal onset resulting in a shorter adult height. We investigated the current incidence of such individuals and that of 30 years ago. METHODS The study subjects are 1,312 consecutive Japanese children referred to Osaka City General Hospital (OCGH) for short stature during 2010-2018, and a cohort of 11,256 individuals in the Ogi Growth Research (OGR, 1979-1992). Individuals with the height standard deviation score <-1.0, the bone age (BA)/chronological age (CA) ratio <0.8 at first visits, and without other identifiable causes of short stature were extracted from the record of OCGH. Similarly, individuals meeting the height and bone age criteria were extracted from the OGR record. The pubertal growth onset was auxologically determined as the upward shift from the prepubertal growth curve fitted to a quadratic function. Earlier-than-expected onset was defined as the onset earlier than the population average +1 year. RESULTS From the OCGH cohort, 55 children (38 boys, 17 girls) met the criteria, and earlier-than-expected onset was observed in 34.2% of boys and 29.4% of girls. In the 73 short individuals with delayed bone age in the OGR cohort, earlier-than-expected onset was less common (13.0% for boys and 14.8% for girls). There was no significant association between the timing of pubertal growth onset and the BA/CA ratio, IGF-1, and midparental height. CONCLUSIONS Earlier-than-expected pubertal growth onset is common in CDG and possibly increasing.